Quantifying Head Leakage Radiation in CyberKnife robotic radiosurgery Systems: A Multi-Modal Approach

Aim The purpose of this study is to measure radiation head leakage of CyberKnife System for in-patient plane and out-of-patient plane using Optically stimulated luminescence dosimeters (OSLD), vented type ionization Chambers, and pressurized ionization chamber-based survey meter and to compare the leakage level with that recommended by the International Electrotechnical Commission (IEC) standard. Materials and Methods In this, CyberKnife (LINAC) having 6MV flattening filter free beam with maximum circular filed size of 6 cm diameter was used. Leakage was measured for both IRIS and FIXED type collimator in fully closed position. To measure the leakage, we had used three different methods, optically stimulated luminescence dosimeters (OSLD), vented ionization Chambers (IC), and pressurized ionization chamber-based survey meter (SM). Leakage measurement points were taken as per the IEC 60601-2-1 report both for in-patient plane and out-of-patient plane. The total number of monitor units (MU) delivered were 500 MU’s. Result The measured average in-patient plane leakage was 0.015% using IC, 0.100% using OSLD and 0.010% using SM, that is well within the tolerance limit of 0.1% according to IEC guidelines. The average leakage for out of patient plane was 0.037%, which is well within the limit of 0.5% as per IEC guidelines. Conclusion The study measured radiation head leakage of the CyberKnife System using OSLD, ionization chambers, and a survey meter. Leakage levels for both in-patient and out-of-patient planes were significantly below the IEC 60601-2-1 standard limits. This confirms the system's compliance with safety guidelines, ensuring minimal radiation exposure.